Method of detecting leakage between heat transfer fluids



Nov. 10, 1953 G. w. EVANS, JR 2,653,728

METHOD OF DETECTING LEAKAGE BETWEEN HEAT TRANSFER FLUIDS Filed June 25.1948 INVENTOR.

17 83 660236 m2 Jr: 14 ydwflb Patented Nov. 10, 1953 UNITED STATESPATENT OFFICE .METHOD OF DETECTIN G BLEAKAGE BE- TWEEN HEAT TRAN SFEBFLUIDS George W. Evans, Jr., Teaneck,'N. J assignor to The LummusCompany, New York, N. "'Y., a corporationof Delaware Application June25, 1948, SerialNo. 35 ,162

3 Claims.

This invention relates to improvements in heat exchange as conducted byan indirect method wherein fluids at different temperatures are placed.in heat exchange relation but out of conmingling of the fluids due toleakage.

A further object of the invention is to minimize the effect of anyleakage which may occur. A still further object. is to render leakage ofone fluid to another readily detectable so that the heat exchangeoperation may be halted before appreciable damage occurs.

Another object is to provide heat exchanger apparatus of improvedconstruction for practicing the invention.

Other objects and advantages of the invention will appear from thefollowing description and the accompanying drawing.

In the drawing, the figure is a view, partly, in vertical section andpartly in elevation, of the heat exchanger apparatus for performing theimproved method.

According to the invention, different fluids are passed respectivelyalong separate confined and spaced courses within a heat exchange zoneand the said. courses are separated by a third fluid.

"This third fluid is maintained in indirect heat exchange relation tosaid courses for heat exchange between the three fluids. In addition toits heat exchange function the third fluid also has two important safetyfunctions. First, it dilutes any leakage which may occur from either ofsaid courses. Second, at least a portion there- 'of is conducted outsideof the heat exchange zone and there inspected to detect such leakage sothat proper precautions may be taken.

The apparatus shown in the drawing for performing the improved methodincludes a vertical heat exchange unit of a shell-and-tube type. Thisunit comprises a cylindrical shell I which is upright in the presentinstance but may be otherwise disposed. At the upper end thereof theshell has inner and outer channels .2 and 3, respectively. At the lower.end of the shell there are inner and outer channels 4 and 5,respectively. Channel 3. is formed by a domesh p membe 6 and a t e sheet1 welded bite 2 tween the base of said member and an annular shensection la. Channel 2 is formed by the tube sheet I, the shell sectionla and a tube sheet 8 welded between said shell section and the body ofthe shell. At the lower end of the shell, the channel 5 is formed by adome-shaped member 9 and tube sheet [0 welded between said member and anannular shell section lb. Channel '4 is formed by the tube sheet 10, theshell section lb and'a tube sheet H welded between said section and thebody of the shell.

. Within the shell there is a nest of tubing of the double-pipe type.The nest includes inner tubes 12 connecting the outer tube sheets 1 andI0, and 'outer tubes l3 surrounding said inner tubes individually andconnecting the inner tube sheetsf8 and H. The outer tubes aresubstantially larger than the inner tubes therein and providesubstantial space surrounding the latter. The lower end member 9 has acentral inlet nozzle II and the upper end member '6 has a central outletnozzle [5. The shell section la has a nozzle I6 opening into the channel2. An elbow drainage conduit section II extends downwardly from theupper face of the tube sheet 10 and laterally outwardly through the"shell section 9 and is welded to both.

The body of the shell has an inlet nozzle l8 located just above the tubesheet II and an outlet nozzle l9 located just below the tube sheet '8.The shell section lb has an expansion joint 20 permitting expansion andcontraction of the inner tubes I2, and the body of the shell has anexpansion joint 2| permitting expansion and contraction of the outertubes l3.

All of the tubes have their end portions rolled into holes in theirrespective tube sheets. As

shown, the upper ends of both the inner tubes and the outer tubes areflush with the upper faces of their respective tube sheets and saidfaces of the sheets are formed with grooves surrounding the tube endsand charged with welding material 22 which joins the tubes to their ofthe elbow drainage conduit section I! is flush with the upper face oftube sheet I0 and similarly welded thereto. Complete drainage isobtainable from the channel 3 through the tubes l2 and the channel 5 andfrom the channel 2 through the tubes 13, the channel 4 and the elbow H.

v the leakage.

'dicated by the meter 29.

3 A lateral conduit section 23 is welded to the outer end of the elbowI! and has an upturned end provided with a springloaded pressure reliefvalve 24. Said section also has a valved tap 25 for drawing off fluidwhen desired. A conduit section or pipe 28, in welded connection to thesection 23, extends upwardly from the latter and has its upper end inwelded connection to the nozzle it which opens into the channel 2.Connected into the pipe 26 there are a pump 21 and a sight glass section28 preferably equipped with flow-indicating means. An electricalconductivity meter 29 is also connected to the pipe 23 to indicatechanges in conduc. tivity in the fluid within the pipe. Through a pipe30 connected to the pipe 26 and having a valve 31 make-up fluid issupplied when required.-

The apparatus is operated as follows to per form the method: The outertube system including the channel 2, the spaces between the tubes thenozzle l9. For assisting heat exchange between the shell-side fluid andthe fluid between the inner and outer tubes the shell is provided withstaggered transverse bailles 32 spaced therealong.

Assume that transfer of heat between a hot shell-side fluid, surroundingthe outer tubes I3,

7 and the fluid within the inner tubes I2 is required. Then, the fluidbetween the tubes I2 and I3, which may be referred to as the third orintermediate fluid, will serve as a heat exchange medium for transfer ofheat from the shell-side fluid to the fluid within the inner tubes I2.In addition to that, the said third fluid has the two safetyfunctionspreviousl mentioned herein. Said fluid assists in isolating theshellside fluid from the fluid in the tubes I 2 and serves as a diluentfor any fluid which may leak into the.

' tubes I3 from either the shell or the inner tubes and thereby preventsor minimizes damage from The said third fluid is also made to serve asan indicator of the leakage. It is led outside of the heat exchange zoneby the pipin 23 and 28 for convenient inspection. Dependent upon thefluids employed, the presence of leakage fluid within the intermediatefluid may be indicated in various ways as by change in color of thelatter fluid, change in pressure, change in viscosity, change in odor,change in electrical conductivity or by other changes either physical orchemical. By observation of the sight glass 28 a change in appearance ofthe fluid can be readily noticed, and increase in pressure will beindicated by blow-off at the relief valve 24. Change in electricalconductivity of the fluid will be in- Samples of the fluid may also bedrawn off through the tap for examination and analysis. Having detectedthe leakage by any of s'aidtests, the operation may be halted and theheat exchanger apparatus drained of fluids, for repairs.

I be circulated by operation of the pump. In-

stead of the closed circulating system shown,

' fresh fluid may be constantly supplied by the pump or the fluid may betemperatu Co ditioned in the closed system by any suitablewell knownmeans. While the third fluid is described as employed as an intermediateheat exchange medium for transfer of heat from one of the primary fluidsto the other it may be temperature conditioned to either heat "or coolthe two other fluids. Any one or all of the fluids may be either liquidor gaseous.

It will be seen that my invention provides for effectual safeguardagainst leakage and damage therefrom and that the desired results areaccomplished in a simple manner and by simple means.

The term leakage, except where qualified, in the specification andclaims is intended to comprehend not merely leakage of liquid, gas orvapor but also the passage of rays or electronic flux from the course ofone of the fluids and into the detecting fluid and whose presence oreffect there can be detected. w

While I have disclosed a verysatisfactory method and apparatus foraccomplishing the desired purposes both the method and apparatus aresusceptible of modification without departing from the invention. .Thedisclosure is merely illustrative and in nowise limiting and theinvention comprehends such modifications as fall within the scope of theappended claims.

I claims 1 1. The method of indirectly transferring heat from a-firstfluid to a second fluid and detecting leakage of either of said fluids,which comprises introducing a liquid having suitable heat'transferqualities into a closed independent path completely within one of thefluids and completely surrounding the other of said fluids, whereby thedesired heat transfer from the first fluid to the second fluid isthrough the liquid, and employing said liquid to indicate leakagethereto of one of said fluids. a

2. The method of indirectly transferring heat from a first fluid to asecond fluid and detecting leakage of either of said fluids, whichcomprises introducing a liquid having suitable heat transfer qualitiesinto a closed independent path completely within one of the fluids andcompletely surrounding the other of said fluids, whereby the desiredheat transfer from the first fluid to the second fluid is through theliquid, circulating a part of the intermediate liquid through an outsideclosed circuit and'therein measuring a significant change in'apredetermined characteristic of the liquid indicating the presencetherein of one of said fluids due to leakage.

3. The method of claim 2 in which the predetermined characteristic ofthe liquid is electrical conductivity.

GEORGE W. EVANS, JR.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 164,757 North -June 22, 1875 1,848,939 Dempsey Mar. 8, 19321,856,618 Brown May 3, 1932 1,920,567 Keck Aug. 1, 1933 1,921,988 GoversAug. 8, 1933 1,994,762 Ennis Mar. 19, 1935 2,379,106 Sanders June 26,1945 FOREIGN PATENTS Number Country Date 273,605 Great Britain. July 12,1927

